Work in our laboratory has continued on the development and characterization of an animal model of human prostatic adenocarcinoma in order to study the immunologic aspects of this disease. Specifically, we wish to examine whether the observed remission of metastatic lesions following treatment of the primary tumor only is the result of an immune response to tumor antigens induced by cryodestruction. Our model system is the Dunning R3327 prostatic adenocarcinoma of the Copenhagen rat. We have induced tumors by the subcutaneous or intraprostatic injection of viable tumor cells. These tumors are macroscopically and histologically identical to those of the human. In addition, metastatic lesions have been found routinely in lymph nodes, lung, liver and less frequently in other organs. We have recently developed an epithelial tissue culture line of the R3327 and have been successful in producing tumors with these cells. These tumors also resemble the human adenocarcinoma and metastasize to the same organs. Early experiments on cryosurgery have shown that this tumor, like the human, is susceptible to cryodestruction by a single freeze. Smaller tumors are completely destroyed within 2 weeks of cryosurgery while larger tumors may require a longer period of time. Current experiments are designed to study the induction of immunity by cryosurgery. BIBLIOGRAPHIC REFERENCES: Lubaroff, D.M., Canfield, L., Feldbush, T.L. and Bonney, W.W. R3327 adenocarcinoma of the Copenhagen rat as a model for the study of the immunologic aspects of prostatic cancer. J. Natl. Cancer Inst., in press, 1977. Lubaroff, D.M. Characterization of an animal model of human prostatic adenocarcinoma. J. Natl. Cancer Inst. Monograph, in press, 1977.